LED emitter with improved white color appearance

ABSTRACT

A lighting apparatus includes a substrate, a plurality of light-emitting dies, a continuous encapsulation structure, and a gel. The plurality of light-emitting dies are disposed on the substrate and spaced apart from one another. The light-emitting dies each are covered with a respective individual phosphor coating conformally. The continuous encapsulation structure has a curved surface disposed over the substrate and encapsulates the light-emitting dies within. The gel is disposed between the encapsulation structure and the phosphor coating for each of the light-emitting dies. The gel contains diffuser particles. The lighting apparatus has a substantially white appearance in an off state when the plurality of light-emitting dies is turned off.

TECHNICAL FIELD

The present disclosure relates generally to light-emitting devices, andmore particularly, to a light-emitting diode (LED) lighting instrumenthaving improved white color appearance.

BACKGROUND

LEDs are semiconductor photonic devices that emit light when a voltageis applied. LEDs have increasingly gained popularity due to favorablecharacteristics such as small device size, long lifetime, efficientenergy consumption, and good durability and reliability. In recentyears, LEDs have been deployed in various applications, includingindicators, light sensors, traffic lights, broadband data transmission,back light unit for LCD displays, and other suitable illuminationapparatuses. For example, LEDs are often used in illuminationapparatuses provided to replace conventional incandescent light bulbs,such as those used in a typical lamp.

One of the performance criteria for LED lighting instruments involve itscolor appearance. For example, it is desirable for an LED lightinginstrument to maintain a substantially white appearance even as it isturned off, since that is more pleasing for the human eye and betterresembles a traditional non-LED lamp. However, existing LED lightinginstruments often suffer from non-white appearances when they are turnedoff. For example, conventional LED light bulbs may still take on ayellowish appearance when they are turned off.

Therefore, although existing LED lighting instruments are generallyadequate for their intended purposes, they have not been entirelysatisfactory in every aspect. An LED lighting instrument capable ofproducing a substantially white appearance when it is turned offcontinues to be sought.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not necessarily drawn to scale oraccording to the exact geometries. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1-2 are diagrammatic fragmentary cross-sectional side view of anexample lighting apparatus using a semiconductor photonic device as alight source according to various aspects of the present disclosure.

FIG. 3 is a diagrammatic fragmentary top view of an example lightingapparatus according to various aspects of the present disclosure.

FIG. 4 is a flowchart illustrating a method of fabricating a lightingapparatus using a semiconductor photonic device as a light sourceaccording to various aspects of the present disclosure.

FIG. 5 is a diagrammatic view of a lighting module that includes aphotonic lighting apparatus of FIGS. 1-3 according to various aspects ofthe present disclosure.

SUMMARY OF THE DISCLOSURE

A lighting apparatus includes a substrate, a plurality of light-emittingdies, a continuous encapsulation structure, and a gel. The plurality oflight-emitting dies are disposed on the substrate and spaced apart fromone another. The light-emitting dies each are covered with a respectiveindividual phosphor coating conformally. The continuous encapsulationstructure has a curved surface disposed over the substrate andencapsulates the light-emitting dies within. The gel is disposed betweenthe encapsulation structure and the phosphor coating for each of thelight-emitting dies. The gel contains diffuser particles. The lightingapparatus has a substantially white appearance in an off state when theplurality of light-emitting dies is turned off.

DETAILED DESCRIPTION

It is understood that the following disclosure provides many differentembodiments, or examples, for implementing different features of variousembodiments. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Forexample, the formation of a first feature over or on a second feature inthe description that follows may include embodiments in which the firstand second features are formed in direct contact, and may also includeembodiments in which additional features may be formed between the firstand second features, such that the first and second features may not bein direct contact. Moreover, the terms “top,” “bottom,” “under,” “over,”and the like are used for convenience and are not meant to limit thescope of embodiments to any particular orientation. Various features mayalso be arbitrarily drawn in different scales for the sake of simplicityand clarity. In addition, the present disclosure may repeat referencenumerals and/or letters in the various examples. This repetition is forthe purpose of simplicity and clarity and does not in itself necessarilydictate a relationship between the various embodiments and/orconfigurations discussed.

Semiconductor devices can be used to make photonic devices, such aslight-emitting diode (LED) devices. When turned on, LEDs may emitradiation such as different colors of light in a visible spectrum, aswell as radiation with ultraviolet or infrared wavelengths. Compared totraditional light sources (e.g., incandescent light bulbs), lightinginstruments using LEDs as light sources offer advantages such as smallersize, lower energy consumption, longer lifetime, variety of availablecolors, and greater durability and reliability. These advantages, aswell as advancements in LED fabrication technologies that have made LEDscheaper and more robust, have added to the growing popularity ofLED-based lighting instruments in recent years.

Nevertheless, existing LED-based lighting instruments may face certainshortcomings. One such shortcoming pertains to unsatisfactory colorappearance in an off state. In more detail, LEDs may rely on a phosphormaterial to convert its light output from one color to another. Forexample, a phosphor material may be used to convert a blue lightproduced by an LED emitter to a more white light. However, conventionaltechniques of applying the phosphor may lead to an LED lightinginstrument having a non-white appearance even when it is turned off,which is undesirable.

According to various aspects of the present disclosure, described belowis an LED lighting instrument having substantially improved whiteappearance in its off state. Referring to FIG. 1, a diagrammaticfragmentary cross-sectional side view of a portion of a lightinginstrument 40 (or a light module) is illustrated according to someembodiments of the present disclosure. The lighting instrument 40includes a substrate 50. In some embodiments, the substrate 50 includesa Metal Core Printed Circuit Board (MCPCB). The MCPCB includes a metalbase that may be made of Aluminum (or an alloy thereof). The MCPCB alsoincludes a thermally conductive but electrically insulating dielectriclayer disposed on the metal base. The MCPCB may also include a thinmetal layer made of copper that is disposed on the dielectric layer. Inother embodiments, the substrate 50 may include other suitablematerials, for example ceramic or silicon. The substrate 50 may containactive circuitry and may also be used to establish interconnections.

The lighting instrument 40 includes a plurality of semiconductorphotonic dies 60 located on the substrate 50. The semiconductor photonicdies function as light sources for the lighting instrument 40. Thesemiconductor photonic dies 60 are LED dies in the embodiments describedbelow, and as such may be referred to as LED dies 60 in the followingparagraphs. In the embodiments discussed herein, the LED dies 60 arephysically spaced apart from one another.

The LED dies 60 each include two oppositely doped semiconductor layers.Alternatively stated, these oppositely doped semiconductor layers havedifferent types of conductivity. For example, one of these semiconductorlayers contains a material doped with an n-type dopant, while the otherone of the two semiconductor layers contains a material doped with ap-type dopant. In some embodiments, the oppositely doped semiconductorlayers each contain a “III-V” family (or group) compound. In moredetail, a III-V family compound contains an element from a “III” familyof the periodic table, and another element from a “V” family of theperiodic table. For example, the III family elements may include Boron,Aluminum, Gallium, Indium, and Titanium, and the V family elements mayinclude Nitrogen, Phosphorous, Arsenic, Antimony, and Bismuth. Incertain embodiments, the oppositely doped semiconductor layers include ap-doped gallium nitride (GaN) material and an n-doped gallium nitridematerial, respectively. The p-type dopant may include Magnesium (Mg),and the n-type dopant may include Carbon (C) or Silicon (Si).

The LED dies 60 also each include a light emitting layer such as amultiple-quantum well (MQW) layer that is disposed in between theoppositely doped layers. The MQW layer includes alternating (orperiodic) layers of active material, such as gallium nitride and indiumgallium nitride (InGaN). For example, the MQW layer may include a numberof gallium nitride layers and a number of indium gallium nitride layers,wherein the gallium nitride layers and the indium gallium nitride layersare formed in an alternating or periodic manner. In some embodiments,the MQW layer includes ten layers of gallium nitride and ten layers ofindium gallium nitride, where an indium gallium nitride layer is formedon a gallium nitride layer, and another gallium nitride layer is formedon the indium gallium nitride layer, and so on and so forth. The lightemission efficiency depends on the number of layers of alternatinglayers and thicknesses. In certain alternative embodiments, suitablelight-emitting layers other than an MQW layer may be used instead.

Each LED die may also include a pre-strained layer and anelectron-blocking layer. The pre-strained layer may be doped and mayserve to release strain and reduce a Quantum-Confined Stark Effect(QCSE)—describing the effect of an external electric field upon thelight absorption spectrum of a quantum well—in the MQW layer. Theelectron blocking layer may include a doped aluminum gallium nitride(AlGaN) material, wherein the dopant may include Magnesium. The electronblocking layer helps confine electron-hole carrier recombination towithin the MQW layer, which may improve the quantum efficiency of theMQW layer and reduce radiation in undesired bandwidths.

The doped layers and the MQW layer may all be formed by one or moreepitaxial growth processes known in the art. For example, these layersmay be formed by processes such as metal organic vapor phase epitaxy(MOVPE), molecular-beam epitaxy (MBE), metal organic chemical vapordeposition (MOCVD), hydride vapor phase epitaxy (HVPE), liquid phaseepitaxy (LPE), or other suitable processes. These processes may beperformed at suitable deposition processing chambers and at hightemperatures ranging from a few hundred degrees Celsius to over onethousand degrees Celsius.

After the completion of the epitaxial growth processes, an LED iscreated by the disposition of the MQW layer between the doped layers.When an electrical voltage (or electrical charge) is applied to thedoped layers of the LED 60, the MQW layer emits radiation such as light.The color of the light emitted by the MQW layer corresponds to thewavelength of the radiation. The radiation may be visible, such as bluelight, or invisible, such as ultraviolet (UV) light. The wavelength ofthe light (and hence the color of the light) may be tuned by varying thecomposition and structure of the materials that make up the MQW layer.For example, the LED dies 60 herein may be blue LED emitters, in otherwords, they are configured to emit blue light. The LED dies 60 may alsoinclude electrodes or contacts that allow the LED dies 60 to beelectrically coupled to external devices.

As is shown in FIG. 1, each LED die 60 is also coated with a phosphorfilm (or a phosphor coating) 70. In various embodiments, the phosphorfilm 70 is conformally coated around the various surfaces (for examplethe top surface and the side surfaces) of each LED die 60. The phosphorfilm 70 may include either phosphorescent materials and/or fluorescentmaterials. The phosphor film 70 is used to transform the color of thelight emitted by an LED dies 60. In some embodiments, the phosphor film70 contains yellow phosphor particles and can transform a blue lightemitted by an LED die 60 into a different wavelength light. By changingthe material composition of the phosphor film 70, the desired lightoutput color (e.g., a color resembling white) may be achieved. Thephosphor film 70 may be coated on the surfaces of the LED dies 60 in aconcentrated viscous fluid medium (e.g., liquid glue). As the viscousliquid sets or cures, the phosphor material becomes a part of the LEDpackage.

The phosphor film 70 for each LED die 60 is physically separated andspaced apart from the phosphor films 70 for other LED dies 60, forexample from the phosphor films 70 coated around adjacent LED dies 60.Therefore, the phosphor film 70 may be said to be coated on each of theLED dies 60 in a localized fashion. In some embodiments, a bulk phosphorfilm may be coated around a plurality of LED dies collectively, and thephosphor-coated LED dies may then be separated and then placed on thesubstrate 50 to ensure that the phosphor films 70 are not in contactwith one another. In other embodiments, the phosphor films 70 may beindividually coated on each LED die 60 to ensure physical separationbetween the phosphor films 70.

The fact that each LED die 60 is coated with a respective localizedphosphor film 70 according to the present disclosure is advantageous,for example with respect to producing a white appearance when the LEDdie 60 is in an off state. In more detail, for many conventional LEDlighting instruments, a bulk phosphor material (or a volume phosphor) iscoated around a plurality of LED dies. The color of the phosphorparticles of the bulk phosphor material may affect the overall colorappearance even when the LED dies are not actively emitting light (i.e.,in an off state). For example, if the bulk phosphor contains primarilyyellow phosphor particles, the overall color appearance of theconventional LED dies may take on a yellowish tone in an off state. Inother words, the conventional LED dies look yellowish when they are notturned on. This is undesirable because a yellowish off-state appearancefor a lighting instrument is not aesthetically pleasing for the humaneye.

In comparison, according to aspects of the present disclosure, thephosphor films 70 are coated locally around each LED die 60, rather thanaround all the LED dies 60 as a whole. This localized phosphor coatingscheme reduces the overall amount of phosphor particles such as yellowphosphor particles. For example, since the spaces between the adjacentLED dies 60 are free of phosphor coating, no phosphor particles aredisposed between adjacent LED dies 60. In addition, the amount ofphosphor particles located over the LED dies 60 are also reduced due tothe localized phosphor coating. As a result, the overall colorappearance for the LED dies 60 may be less yellow and more whitecompared to conventional LED dies. Thus, the lighting instrument of thepresent disclosure (i.e., utilizing the LED dies 60) is also able toproduce a substantially white appearance in its off state.

Note that yellow phosphor particles are used herein merely as an exampleto illustrate the effect of colored phosphor particles on the colorappearance of the LED dies. The same concept may apply if the phosphorcontains red, green, or phosphor particles of other different colors.

Although the more white appearance is one of the advantages of theembodiments of the lighting instrument shown herein, it is not the onlyadvantage, nor is it required for all embodiments. Other embodiments mayoffer different advantages that are not necessarily discussed herein.

In some embodiments, the spacing between the adjacent phosphor-coatedLED dies 60 is configured to minimize the influence from coloredphosphor particles while not sacrificing chip area too much. In moredetail, the greater the distance that separates the adjacent LED dies60, the more the overall color appearance will approach a white color.However, the greater distance between adjacent LED dies 60 results in alarger chip area, which is costly, cumbersome, and inefficient. Hence,an optimization trade-off may be made to select a die separationdistance range that achieves good white color appearance and stillmaintains a small enough chip package.

For example, as is shown in FIG. 1, each phosphor-coated LED die 60 mayhave a horizontal or lateral dimension 80, and an optimized spacingbetween adjacent phosphor-coated LED dies 60 may be measured by anoptimized distance 90. Accordingly, there is a correlation between thelateral dimension 80 of the phosphor-coated LED die 60 and the optimizeddistance 90 separating these dies. In other words, the optimizeddistance 90 may be defined as a function of the lateral dimension 80, orvice versa.

Referring now to FIG. 2, a more detailed illustration of the lightinginstrument 40 is shown as a diagrammatic cross-sectional side view. Thelighting instrument 40 includes a plurality of LED dies 60 disposed onthe substrate 50. As discussed above, the LED dies 60 are each coatedwith a phosphor film 70 in a localized fashion, such that the phosphorfilms 70 coated around different LED dies 60 are not in physical contactwith one another.

The lighting instrument 40 also includes a diffuser cap 110. Thediffuser cap 110 provides a cover for the LED dies 60 therebelow. Stateddifferently, the LED dies 60 may be encapsulated by the diffuser cap 110and the substrate 50 collectively. The substrate 50 may or may not becompletely covered by the diffuser cap 110. In some embodiments, thediffuser cap 110 has a curved surface or profile. In some embodiments,the curved surface may substantially follow the contours of asemicircle, so that each beam of light emitted by the LED dies 60 mayreach the surface of the diffuser cap 110 at a substantially rightincident angle, for example, within a few degrees of 90 degrees. Thecurved shape of the diffuser cap 110 helps reduce Total InternalReflection (TIR) of the light emitted by the LED dies 60. In someembodiments, the diffuser cap 110 has a textured surface for furtherscattering of the incident light.

In some embodiments, the space between the LED dies 60 and the diffusercap 110 may be filled by an optical-grade silicone-based adhesivematerial 120, also referred to as an optical gel 120. Diffuser particlesmay be mixed within the optical gel 120 in these embodiments so as tofurther diffuse light emitted by the LED dies 60. In other embodiments,the space between the LED dies 60 and the diffuser cap 110 may be filledby air.

The substrate 50 is located on a thermal dissipation structure 200, alsoreferred to as a heat sink 200. The heat sink 200 is thermally coupledto the LED dies 60 through the substrate 50. The heat sink 200 isconfigured to facilitate heat dissipation to the ambient atmosphere. Theheat sink 200 contains a thermally conductive material, such as a metalmaterial. The shape and geometries of the heat sink 200 may be designedto provide a framework for a familiar light bulb while at the same timespreading or directing heat away from the LED dies 60. To enhance heattransfer, the heat sink 200 may have a plurality of fins 210 thatprotrude outwardly from a body of the heat sink 200. The fins 210 mayhave substantial surface area exposed to ambient atmosphere tofacilitate heat transfer. In some embodiments, a thermally conductivematerial may be disposed between the substrate 50 and the heat sink 200.For example, the thermally conductive material may include thermalgrease, metal pads, solder, etc. The thermally conductive materialfurther enhances heat transfer from the LED dies 60 to the heat sink200.

FIG. 3 is a simplified diagrammatic top view of the lighting instrument40 according to some embodiments. For the sake of providing an example,nine phosphor-coated LED dies 60 are secured to the substrate 50 and arearranged in three rows and three columns. In other embodiments, anyother number of LED dies may be used and may be arranged in othersuitable configurations. These LED dies 60 and their respective phosphorfilms 70 are covered by a diffusive and transparent gel 120, which ishoused by a diffuser cap 110.

Since the LED dies 60 are each coated by the phosphor film 70, they arenot directly visible in the top view in FIG. 3. Therefore, one of thephosphor-coated LED dies 60 is illustrated separately near the top leftcorner of FIG. 3 to specifically show the contours or boundaries of theLED die 60. The boundaries of the LED die 60 are shown as broken lines,so as to indicate that the LED die 60 is not directly visible since itis covered by the phosphor film 70. Similarly, the phosphor films 70 arenot directly visible in the top view either, since they covered by thediffusive gel 120. But for the sake of illustration, the contours orboundaries of the phosphor films 70 are still shown herein as brokenlines.

As discussed above, unlike conventional LED-based lighting instruments,the phosphor films 70 are coated locally around each LED die 60 in thelighting instrument 40, rather than being coated as a volume phosphoraround all of the LED dies collectively. Therefore, the phosphor films70 herein are separated from other phosphor films, thereby reducing thepresence of the colored phosphor particles under the diffuser cap 110.As such, the overall color appearance for the LED dies may be lessyellow compared to conventional LED dies.

FIG. 4 is a flowchart of a method 300 for fabricating a lightingapparatus using a semiconductor photonic device as a light sourceaccording to various aspects of the present disclosure. The method 300includes a step 310, in which a substrate is provided. The substrate maybe a PCB substrate, a ceramic substrate, a silicon substrate, or anothersuitable substrate. The method 300 includes a step 320, in which aplurality of LED dies is placed on the substrate. The LED dies are eachcoated with a respective phosphor film. The phosphor film for each LEDdie is conformally coated around the LED die. The phosphor film for eachLED die is physically spaced apart from the phosphor films for other LEDdies. In some embodiments, the step 320 includes configuring an optimalseparation distance between adjacent phosphor-coated LED dies. Theoptimal separation distance is a function of a lateral dimension of oneof the phosphor-coated LED dies. The method 300 includes a step 330, inwhich a diffusive and transparent gel is applied over the substrate andon the LEDs coated with the phosphor films. The method 300 includes astep 340, in which a diffuser cap is installed over the substrate. Thediffuser cap provides a housing for the diffusive and transparent geland the LED dies coated with the phosphor films.

Additional processes may be performed before, during, or after theblocks 310-340 discussed herein to complete the fabrication of thelighting apparatus. For the sake of simplicity, these additionalprocesses are not discussed herein.

FIG. 5 illustrates a simplified diagrammatic view of a lighting module400 that includes some embodiments of the lighting instrument 40discussed above. The lighting module 400 has a base 410, a body 420attached to the base 410, and a lamp 430 attached to the body 420. Insome embodiments, the lamp 430 is a down lamp (or a down light lightingmodule).

The lamp 430 includes the lighting instrument 40 discussed above withreference to FIGS. 1-4. In other words, the lamp 430 of the lightingmodule 400 includes an LED-based light source, wherein the LED dies arephosphor coated in a localized manner. Due at least in part to theadvantages discussed above, the LED packaging for the lamp 430 can takeon a substantially white appearance in its off state, whereasconventional LED lighting instruments often times look yellow when theyare turned off.

One of the broader forms of the present disclosure involves a lightingapparatus. The lighting apparatus includes: a substrate; a plurality oflight-emitting dies disposed on the substrate and spaced apart from oneanother, the light-emitting dies each being covered with a respectiveindividual phosphor coating; and an encapsulation structure disposedover the substrate and encapsulating the light-emitting dies within;wherein the lighting apparatus has a substantially white appearance atan off state.

In some embodiments, the lighting apparatus further includes: a geldisposed between the encapsulation structure and the light-emittingdies.

In some embodiments, the diffusive gel is transparent and containsdiffuser particles.

In some embodiments, the light-emitting dies each include alight-emitting diode (LED).

In some embodiments, the light-emitting dies are each configured to emitblue light.

In some embodiments, the encapsulation structure includes a diffuser capconfigured to scatter light.

In some embodiments, the phosphor coating is conformally coated aroundeach light-emitting die.

In some embodiments, the phosphor coating for each respectivelight-emitting die is separated from the phosphor coatings for adjacentlight-emitting dies by a distance.

In some embodiments, the distance is a function of a lateral dimensionof the LED die.

Another one of the broader forms of the present disclosure involves aphotonic lighting module. The photonic lighting module includes: aboard; one or more light-emitting diodes (LEDs) located on the board; alocalized phosphor film coated around each of the one or more LEDs in amanner such that the one or more LEDs take on a substantially whiteappearance when the one or more LEDs are not actively emitting light;and a diffuser cap located over the board and housing the one or moreLEDs within.

In some embodiments, the photonic lighting module further includes adiffusive and transparent material located on the one or more LED diesand housed within the diffuser cap.

In some embodiments, the one or more LEDs are each configured to emitblue light; and the phosphor film contains yellow phosphor particles.

In some embodiments, the one or more LEDs include a plurality of LEDsspaced part from one another.

In some embodiments, the phosphor film for each LED is free of being inphysical contact with other phosphor films for other LEDs.

In some embodiments, a spacing between adjacently-located LEDs iscorrelated with a size of the LEDs.

In some embodiments, the phosphor film is conformally coated around eachof the one or more LEDs.

Still another one of the broader forms of the present disclosureinvolves a method of fabricating a lighting apparatus. The methodincludes: providing a substrate; placing a plurality of light-emittingdiode (LED) dies on the substrate, the LED dies each being coated with arespective phosphor film, wherein the phosphor film for each LED die isphysically spaced apart from the phosphor films for other LED dies, andwherein the LED dies are placed on the substrate according to an optimalseparation distance between adjacent LED dies; applying a diffusive andtransparent gel over the substrate and on the LEDs coated with thephosphor films; and installing a diffuser cap over the substrate, thediffuser cap housing therein the diffusive and transparent gel and theLED dies coated with the phosphor films.

In some embodiments, the phosphor film for each LED die is conformallycoated around the LED die.

In some embodiments, the optimal separation distance is a function of alateral dimension of one of the LED dies.

In some embodiments, the placing the plurality of LED dies is performedin a manner such that the LED dies assume a substantially whiteappearance when the LED dies are turned off.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the detailed description thatfollows. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A lighting apparatus, comprising: a substrate; aplurality of light-emitting dies disposed on the substrate and spacedapart from one another, the light-emitting dies each being covered witha respective individual phosphor coating conformally; a continuousencapsulation structure having a curved surface disposed over thesubstrate and encapsulating the plurality of light-emitting dies within;and a gel disposed between the encapsulation structure and the phosphorcoating for each of the light-emitting dies, wherein the gel containsdiffuser particles; wherein the lighting apparatus has a substantiallywhite appearance when the plurality of light-emitting dies is turnedoff.
 2. The lighting apparatus of claim 1, wherein the gel istransparent and is in direct physical contact with outer surfaces of theindividual phosphor coating for each light-emitting die.
 3. The lightingapparatus of claim 1, wherein the light-emitting dies each include alight-emitting diode (LED).
 4. The lighting apparatus of claim 1,wherein the light-emitting dies are each configured to emit blue light.5. The lighting apparatus of claim 1, wherein the encapsulationstructure includes a diffuser cap configured to scatter light.
 6. Thelighting apparatus of claim 1, wherein the phosphor coating for eachrespective light-emitting die is separated from the phosphor coatingsfor adjacent light-emitting dies by a distance.
 7. The lightingapparatus of claim 6, wherein the distance is a function of a lateraldimension of the light-emitting die.
 8. A photonic lighting module,comprising: a board; a plurality of light-emitting diodes (LEDs) locatedon the board; a localized phosphor film conformally coated around eachof the plurality of LEDs in a manner such that the photonic lightingmodule has a substantially white appearance when the plurality of LEDsis turned off; and a continuous cap having a curved surface located overthe board and housing the plurality of LEDs within; and a diffusive andtransparent material located over the localized phosphor film for eachof the plurality of LEDs, wherein the diffusive and transparent materialis housed within the cap.
 9. The photonic lighting module of claim 8,wherein the diffusive and transparent material is in direct physicalcontact with outer surfaces of the localized phosphor film coated aroundeach of the plurality of LEDs.
 10. The photonic lighting module of claim8, wherein: the plurality of LEDs is each configured to emit blue light;and the localized phosphor film contains yellow phosphor particles. 11.The photonic lighting module of claim 8, wherein the plurality of LEDsis spaced part from one another.
 12. The photonic lighting module ofclaim 11, wherein the localized phosphor film for each LED is free ofbeing in physical contact with other phosphor films for other LEDs. 13.The photonic lighting module of claim 11, wherein a spacing betweenadjacently-located LEDs is correlated with a size of the LEDs.
 14. Alighting apparatus, comprising: a substrate, wherein the substrate is aprinted circuit board (PCB), a ceramic substrate, or a siliconsubstrate; a plurality of light-emitting diode (LED) dies located overthe substrate, the LED dies each being coated with a respective phosphorfilm conformally, wherein the phosphor film for each LED die isphysically spaced apart from the phosphor films for other LED dies, andwherein each LED die is separated from adjacent LED dies according to apredetermined optimal separation distance; a diffusive and transparentgel located over the substrate and over the LEDs; and a continuous caphaving a curved surface located over the substrate, the cap housingtherein the diffusive and transparent gel and the plurality of LED dies;wherein the lighting apparatus has a substantially white appearance whenthe LED dies are turned off.
 15. The lighting apparatus of claim 14,wherein the optimal separation distance is a function of a lateraldimension of one of the LED dies.
 16. The lighting apparatus of claim 1,wherein the substrate is a printed circuit board (PCB), a ceramicsubstrate, or a silicon substrate.
 17. The lighting apparatus of claim14, further comprising a heat sink wherein the substrate is located onthe heat sink and the heat sink is thermally coupled to the LED diesthrough the substrate.
 18. The lighting apparatus of claim 17, whereinthe heat sink has a plurality of fins that protrude outwardly from abody of the heat sink.